Question

I’m a newcomer to Ruby just using this forum to help understand the language while I code a sample application to hone my skills.

I’ve tried to set up a has many relationship between Product & Media. I suspect the challenge I”m having is because of the plural form medium, but not sure how to troubleshoot it.

class CreateMedia < ActiveRecord::Migration
  def change
    create_table :media do |t|
      t.string :type
      t.string :alt
      t.boolean :is_primary
      t.string :url_tiny
      t.string :url_small
      t.string :url_regular
      t.string :url_large
      t.string :title

      t.timestamps
    end
  end
end

 class Media < ActiveRecord::Base
  attr_accessible :alt, :is_primary, :title, :type, :url_large, :url_regular, :url_small, :url_tiny
  belongs_to :product
end

class Product < ActiveRecord::Base
   attr_accessible :assoc_product,:product_id, :merch_associations, :aux_description, :buyable, :long_description, :name, :on_special, :part_number, :release_date, :short_description, :withdraw_date, :occasion
  has_and_belongs_to_many :categories
  has_many :merch_associations
  has_many :assoc_products, :through => :merch_associations
  has_many :media
 ...

When I run this (note dress_media is a populated Media object array):

 products[i].media << dress_media[m]

I get this in the error console:

uninitialized constant Product::Medium

I looked in the DB and the table is indeed called Media, not medium. So I thought it should have been the plural right? (This code was generated from the rails generator)

Like I say I’m new to Rails so if someone can point me in the right direction to create this one to many between Product & Media, that would be great?

Answer 1

As I understand, you have a model called ‘Media’. Note that ‘Media’, as you mention in your question, is already a plural. The correct would be having a model called ‘Medium’ and the following relationships:

class Medium < ActiveRecord::Base
    attr_accessible :alt, :is_primary, :title, :type, :url_large, :url_regular,:url_small, :url_tiny
    belongs_to :product
end

and

class Product < ActiveRecord::Base
   attr_accessible :assoc_product,:product_id, :merch_associations, :aux_description,     :buyable, :long_description, :name, :on_special, :part_number, :release_date,     :short_description, :withdraw_date, :occasion
   has_and_belongs_to_many :categories
   has_many :merch_associations
   has_many :assoc_products, :through => :merch_associations
   has_many :media
   ...
end

At sometime you might want to set or overwrite Rails singularizations and pluralizations. I don’t recommend doing it in that specific case, but take a look at http://blog.thefrontiergroup.com.au/2011/06/pluralizations-and-singularizations-inflections-in-rails-3/ just to know how to do it.

Note that if you create a model called ‘Medium’, the database table will be called ‘Media’.